Here's What Investors Should Know About AstraZeneca's COVID Vaccine Data

AstraZeneca (AZN 6.05%) published data from its phase 3 clinical trials in The Lancet, but the full data set didn't answer the most important question about why a half-dose followed by a full dose worked better than two full doses. In this video from Motley Fool Live, recorded on Dec. 14, Corinne Cardina, bureau chief of healthcare and cannabis, and Fool.com contributor Brian Orelli discuss the issue and potential reasons for the phenomenon. They also talk about why investors shouldn't be particularly worried about any delay the confusing data might create.

Corinne Cardina: So, moving on to another vaccine developer, AstraZeneca actually published their data in The Lancet. I'm going to go ahead and post that link in the chat. If anyone's interested in seeing that. Brian, did this peer-reviewed report contain any new information for investors?

Brian Orelli: I mean, it had a lot of data for certain areas, but the supplementary data, there's a PDF of 49 pages, so that tells you how much data they actually released from the trial. But the top-line result is still the most important thing for investors. The mystery here is that the full -- two full -- doses gained a 62% efficiency and the half-dose at the beginning and then a full dose for the second dose gave 90% efficiency, but there was fairly small numbers in that group. So it's hard to determine whether it's actually 90% or it could be higher; it could be lower. I think it's really hard to interpret the data, and the other way things should have combined clinical trials, which you can do if you have that as you plan to begin with. But then certainly, that doesn't seem to be the case, because they use different controls. One group got meningococcal vaccine as their control and another group got placebo, as you know, a saline solution, as the control.

Cardina: Yeah, we'll be keeping an eye on that. There has been some hypothesizing that the half-dose primes the person's immune system before they get that full dose.

Orelli: I think the other hypothesis here is that a full dose might actually be blocking the second dose. So because the way AstraZeneca's vaccine works is, it uses, like, a cold virus to deliver the DNA that makes the protein that results in the vaccine for the coronavirus. So the idea is that if you get a full dose to begin with, then you might be overreacting to the second dose and be inhibiting the cold virus before it can infect the cells and create the protein that's required for the vaccine.

Cardina: Absolutely. Hopefully, we will find out more about that in the future. So AstraZeneca, of course, has made a pledge not to profit off its vaccine during the pandemic. That doesn't mean that it's stopped, couldn't benefit from a boost should it receive regulatory clearances. Brian, what should investors know about this stock before investing?

Orelli: Yeah, I mean, I think AstraZeneca can clearly benefit after the pandemic ends, and its vaccine has some definite advantages, storage requirements. So I think it can definitely work in rural areas better than Moderna's and Pfizer and BioNTech. From an investor perspective, AstraZeneca has some time to figure out the dosing since any profits they make right now wouldn't actually be profits. From an investor perspective, AstraZeneca being hurt or even having to take longer is not really a big deal because they're not going to make any profit from it anyway. From a health perspective, obviously, we'd like to see it as a high end of efficacy as possible, and as early as possible.